Osmotic systems manufactured in the form of an osmotic device for the administration of a beneficial agent are known in U.S. Pat. Nos. 3,845,770 and 3,916,899 both issued to inventors Felix Theeuwes and Takeru Higuchi, and in U.S. Pat. No. 4,016,880 issued to patentees Felix Theeuwes and Nalinkant Damani. The osmotic systems disclosed in these patents are made of a thick semipermeable wall that surrounds a compartment containing a beneficial drug. The semipermeable wall is permeable to the passage of an external fluid, and it is substantially impermeable to the passage of drug. The osmotic systems have a passageway through the semipermeable wall for delivering the drug from the osmotic system. The osmotic systems are designed and manufactured with a thick wall that is substantially nonexpandable and inflexible in the presence of a beneficial agent and fluids found in the environment of use. These prior art osmotic systems are extraordinarily effective for delivering a beneficial agent that dissolves in fluid imbibed into the compartment and forms a true solution that is hydrodynamically delivered from the system. The osmotic systems are ideally suited for extended gastrointestional therapy, because they continuously deliver a drug during the prolonged time the system travels through the entire length of the gastrointestional tract. More particularly, these osmotic systems have a practical value in gastrointestional therapy as they deliver a drug beginning with their entrance into the stomach and continuously throughout the gastrointestional tract until they exit the tract through the anus.
The above discussed osmotic systems represented an outstanding and pioneering advancement in the delivery art, and they are useful for dispensing a drug throughout the entire environment of the gastrointestional tract. Now, it has been discovered a need exists for an osmotic delivery system that preferably delivers a drug in preselected regions of the gastrointestional tract, mainly the stomach and the small intestine. The need exists, because certain drugs are absorbed from these preferred regions, the stomach and the small intestine.
Moreover, there are instances when it is contraindicated to deliver a drug in a certain region of the gastrointestional tract, for example, the large intestine including the colon. The delivery of a drug in the large intestine often is contraindicated particularly, when the drug unwantingly alters the floral pattern of the large intestine. It will be appreciated by those versed in the delivery art, that if a novel and useful osmotic system were provided for delivering a drug substantially in the stomach and small intestine, such an osmotic system would have a definite use, represent an unexpected advancement and substantial contribution to the art, and have a positive value in the fields of medicine and allied therapies.